It was distinctly okay. If I was to recommend any of the places that Wimonpak has on airbnb, I would not recommend this one.
Don't misunderstand, it isn't a bad place, it was pretty clean and well decorated, but the other units are nicer (due to some problem, she asked us to stay in a different apartment, on the second floor, the first night).
The other apartment, while more expensive I think, had a nice balcony and an induction cooker so one could cook their own food, whereas Cool Studio 1 did not have one, forcing us to eat out or bring food back every meal. Not a huge problem, but I might have expected kitchen facilities.
The location is great though! It is about a 10 minute walk to the river boat taxi, which is by far the easiest way to get to the touristy part of Bangkok where all the sights are. There is also a supermarket nearby and the area feels very much like "authentic" Bangkok.
Again, I would recommend the location and winonpak's listings, but maybe not this one. There were several cockroaches in the bathroom (which wasn't too terrible; I might expect it for Southeast Asia). The most annoying thing was that because of the first floor location, you can hear everyone as they walk downstairs and go through the two doors to enter or exit the binding; it is quite loud. Besides that, it is a very quiet place.
So, to sum up, I would instead recommend paying a little more and taking an apartment on the second or third floor.